1. Technical Field
The present invention relates generally to suspensions for supporting read/write heads over recording media. In particular, the present invention is an integrated lead head suspension having a load beam etched from laminated sheets of material and a flexure additively fabricated by depositing conductors on a base layer.
2. Background of the Invention
Head suspensions are well known and commonly used with dynamic magnetic and/or optical storage devices or drives with rigid disks. The head suspension is a component within the disk drive which supports a read/write head over a desired position on the storage media (typically a data track on a spinning, rigid disk) where information is to be retrieved or transferred. A head suspension includes a load beam having a flexure to which a head slider having a read/write head is to be mounted.
The load beam includes a mounting region at a proximal end, a rigid region adjacent to a distal end and a spring region between the mounting region and rigid region. The spring region is relatively resilient and provides a downward bias force at the distal tip of the load beam for holding the read/write head near the spinning disk in opposition to an upward force created by an air bearing over the disk. The head slider allows the read/write head to xe2x80x9cflyxe2x80x9d above the disk on this air bearing. The flexure is to allow pitch and roll motion of the head slider and read/write head as they move over the data tracks of the disk. Via the mounting region of the load beam, the head suspension can be mounted to an actuator arm for coupling the head suspension to a voice coil or other type of actuator. Both linear and rotary type actuators are known in the art.
Manufacturers of head suspensions face competing design considerations. On one hand, it is important that head suspensions have relatively low mass and be relatively flexible. This is necessary to allow the head slider and read/write head to fly closely above the surface of the spinning data disk (on the order of 0.1 xcexcm) without colliding with the disk (xe2x80x9ccrashingxe2x80x9d) and still allow for imperfections in the disk surface and/or variations in the air bearing on which the head slider is flying. Flexibility is particularly important in the sensitive spring and flexure areas. Also, when the actuator stops the head suspension over a particular data track to read or write information, the deceleration can cause an inertial shock in the head suspension which causes transient vibrations. Data cannot be stored or retrieved until these vibrations substantially subside. In general, the lower the mass of the head suspension, the lower the inertial shock and ensuing transient vibrations. Therefore, a lower mass head suspension can decrease data access times. Finally, a lower mass head suspension requires less energy for the actuator to move the read/write head over the data disk surface. This can be particularly important in systems in which low energy consumption is advantageous, such as battery powered computer systems. In sum, a lower mass head suspension can either decrease access times, use less energy, or both.
On the other hand, head suspensions carry electrical components. For example, electrical read/write signals must be transferred to and from the read/write head, across the head suspension, to processing electronics. Electrical conductors can be included on the head suspension to facilitate this transfer of signals. These conductors can consist of copper wires encapsulated in a plastic tubing or coated with a dielectric material. Such standard conductors can have a large effect on head suspension performance. For example, a standard conductor placed atop a thin suspension can more than double a spring region""s stiffness and detract from the ability of a spring region to adjust to variations in the surface of the disk. The effect of standard conductors on a flexure region, the thinnest and most delicate spring in the head suspension, is even more pronounced. Further, electrical components such as conductors add mass to the head suspension.
To help alleviate the difficulties in including electrical components on the head suspension, it is known to form such electrical components integrally with the head suspension. Such head suspensions are known as integrated lead or wireless head suspensions. Various methods exist for manufacturing head suspensions in this way.
One such method involves an additive or deposition process wherein multiple layers of different materials are built up on a substrate layer by sputtering, plating, chemical vapor deposition, ion beam deposition, evaporation, photolithographic techniques or other known processes. For example, a substrate layer can be formed from a rigid material such as stainless steel, an intermediate layer can be polyimide or other dielectric, and an upper layer can be an electrical conductor such as copper and formed in strips extending between the desired locations on the head suspension. Such additive techniques are known in the art and disclosed in, for example, U.S. Pat. No. 5,454,158 for Method of Making Integral Transducer-Suspension Assemblies for Longitudinal Recording, issued to Fontana, et al. on Oct. 3, 1995 and U.S. Pat. No. 5,111,351 for Integrated Magnetic Read/Write Head/Flexure/Conductor Structure, issued to Hamilton on May 5, 1992.
Using additive methods it is possible to form relatively thin, and therefore, flexible and relatively low mass electrical components. As such, the head suspension on which such components are formed can remain relatively flexible and low in mass. However, using additive methods can be relatively expensive because the equipment used to carry out additive processes is designed to accommodate relatively small semi-conductor components. Thus, relatively larger head suspension components can be manufactured in only relatively small batches. Accordingly, using additive methods to manufacture relatively large quantities of head suspension components can become time consuming and expensive.
A second method for forming electrical components integrally with a head suspension involves a subtractive method in which the starting material has a plurality of laminated layers which are chemically etched or otherwise removed to form the electrical components. For example, the starting material can be a laminated sheet having a lower layer of stainless steel or other rigid material, a middle layer of dielectric such a polyimide, and an upper layer of electrically conductive material such as copper. The layers may be successively chemically etched using known methods to form electrical leads or other electrical components from the conductive layer which are insulated from the rigid layer by the dielectric layer. Such methods are known in the art and disclosed in U.S. Pat. No 5,598,307, issued Jan. 28, 1997 to Bennin for Integrated Gimbal Suspension Assembly, which is hereby incorporated by reference in its entirety.
At present, using subtractive methods, it is problematic to produce electrical leads or other components that are as thin, low mass, and flexible as those which can be produced using additive methods. However, it is generally less expensive to manufacture head suspension using subtractive methods.
It is evident that there is a continuing need for improved methods for fabricating head suspensions and/or parts thereof. In particular, electrical components formed integrally with the head suspension should be suitably thin, low mass and flexible and yet relatively cost effective to manufacture.
The present invention is an integrated lead head suspension having a load beam and a flexure. The load beam is formed from a laminated sheet having a rigid base layer and an electrically conducting layer. The load beam includes a mounting region at a proximal end, a rigid region adjacent to a distal end, and a spring region between the mounting region and the rigid region. Electrical conductors are formed on the load beam by etching the electrically conducting layer. The flexure is for supporting a head slider and is formed by depositing electrical conductors over a base layer. The flexure is attached to the distal end of the load beam and the electrical conductors of the flexure are electrically interconnected with the electrical conductors of the load beam.